Proac problem: tweeters or crossover?

Twoleftears, as you may be aware tube amplifiers having output transformers should not be operated without a speaker or equivalent load being connected, especially when signals are being put through them. Assuming you are still using the Cary SET amp listed in your system description, it occurs to me that when you connected the amp to just the high frequency section of the speakers you were running the amp unloaded across those parts of the spectrum where the great majority of the energy of most music is concentrated. I say this given that the crossover point of your speakers is a bit higher than 3 kHz, as shown in Stereophile's measurements, and the rolloff of the high pass part of the crossover below that point appears to be a fairly rapid 18 db/octave.

Which leads me to suggest two things:

1)Don't do it no more :-)

2)I'm not certain of this, but it seems to me to be possible that the anomalous sonics you heard when only the high pass sections of the speakers were connected might have been the result of amplifier misbehavior resulting from the improper loading. So I'm not sure that any of those observations were meaningful.

And perhaps the differences you observed with the new tweeters vs. the original ones were simply due to what would under normal circumstances be inconsequential differences in their parameters.

What I would suggest is that with a little Googling you should be able to find a test record or CD you can order which has a set of 1/3 or 1/2 octave warble tones, or something similar, the set of tones covering the entire audible spectrum. That would allow you to very readily tell whether the tweeters and their associated crossover elements are working properly or not, which I don't think any of us can say at this point with any certainty.

Good luck. Regards,
-- Al

Almarg: will do re. test CD. I should have added earlier that I've inserted an Ayre AX-7e into the system (that led to initial scrutiny of the speakers).

Zd542, as per original post, Modern Audio, the distributors for Proac in the US, told me to acquire the Scanspeak D2010s. When I queried them as to whether they were identical, or whether Proac did some mods to them or not, they claimed that they were identical. For a while there, there was quite a lot of "cloning" of the 2.5 in DIY designs, so there's a good deal of discussion of components on the web.

The SR Signature 2/3s are like this: at the amplifier end, there is a spade, immediately after which the cable splits into two, so there are two separate runs, physically, all the way to the speaker. I don't know what's going on inside, but the run for the woofer is thicker, which is the only way you can tell the two of them apart.

Dover: according to the web, the 2.5s use Ansar Supersound caps. I'm keeping my fingers crossed that there's nothing broke.

With the crossover at 3kHz as Almarg stated, I think what you are hearing is normal. I had a pair of Paradigm Studio 60s that experienced a tweeter failure, the dome disintegrated. When I replaced it I first listened to the tweeter separately as you are doing and heard what you described. I compared it to the good speaker's tweeter as I was concerned.
You could measure the resistance of the tweeter and see if there is any difference between speakers. If there is a difference then there may be an issue with the crossover, but as you say both sound the same I doubt it. As for break in, not the issue here.
The real question is, how do the speakers sound when being played normally? I think you purchased an extra set of tweeters.

"The SR Signature 2/3s are like this: at the amplifier end, there is a spade, immediately after which the cable splits into two, so there are two separate runs, physically, all the way to the speaker. I don't know what's going on inside, but the run for the woofer is thicker, which is the only way you can tell the two of them apart."

What they did was take 2 separate pairs of speaker cables and terminate them at the amp end with the same spades for easier connection. Otherwise you would have to double up and put 2 sets of spades in 1 binding post because most amps only give you 1 pair to work with. Since Synergistic always recommended using the 2's and the 3's together, they ended up taking the exact setup you have with the 2 pairs terminated together at the amp end, and wrap both pairs in 1 sleeve, making it look like one pair of cables. They renamed it the Signature 10.

What I said about them in my first post still applies. Given your problem, and how different those speaker cables sound from each other, I wouldn't want them in the system until you solve your problem. So you can either use different cables, or just connect 1 of the 2 pairs of the Synergistic to the speakers and use the binding post jumpers. Just be sure to cover the spades on the cables you don't use. And it doesn't matter which pair you use. Try it both ways and pick ones that sound best.

"The real question is, how do the speakers sound when being played normally? I think you purchased an extra set of tweeters.
Timrhu (System | Reviews | Threads | Answers | This Thread)"

That's a good question. After reading your post again, I can't tell if the problem exists during normal operation. A assume there's a problem otherwise you wouldn't post.

Regarding my suggestion of a test record or CD providing 1/3 octave warble tones, Stereophile's Test CD 3 appears to be suitable (specifically tracks 17, 18, and 19), and is available here. Further description is provided here.

A possible limitation of that particular test CD, though, is that as far as I can tell it may not provide separate tones for the left and right channels. If so, and given that your Ayre integrated amp apparently does not provide a balance control, you would probably have to disconnect one speaker, or one input channel to the amp, in order to accurately assess the other speaker.

Good luck. Regards,
-- Al